 <osandov@fb.com>
---
 fs/fuse/file.c | 40 ++++++++++++++++++++++++++--------------
 1 file changed, 26 insertions(+), 14 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index f1ef77a0be05..654e21ee93fb 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -100,7 +100,7 @@ static void fuse_release_end(struct fuse_mount *fm, struct fuse_args *args,
 	kfree(ra);
 }
 
-static void fuse_file_put(struct fuse_file *ff, bool sync)
+static void fuse_file_put(struct fuse_file *ff, bool sync, bool isdir)
 {
 	if (refcount_dec_and_test(&ff->count)) {
 		struct fuse_release_args *ra = &ff->args->release_args;
@@ -110,7 +110,9 @@ static void fuse_file_put(struct fuse_file *ff, bool sync)
 			fuse_file_io_release(ff, ra->inode);
 
 		if (!args) {
-			/* Do nothing when server does not implement 'open' */
+			/* Do nothing when server does not implement 'opendir' */
+		} else if (!isdir && ff->fm->fc->no_open) {
+			fuse_release_end(ff->fm, args, 0);
 		} else if (sync) {
 			fuse_simple_request(ff->fm, args);
 			fuse_release_end(ff->fm, args, 0);
@@ -131,8 +133,17 @@ struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid,
 	struct fuse_file *ff;
 	int opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
 	bool open = isdir ? !fc->no_opendir : !fc->no_open;
+	bool release = !isdir || open;
 
-	ff = fuse_file_alloc(fm, open);
+	/*
+	 * ff->args->release_args still needs to be allocated (so we can hold an
+	 * inode reference while there are pending inflight file operations when
+	 * ->release() is called, see fuse_prepare_release()) even if
+	 * fc->no_open is set else it becomes possible for reclaim to deadlock
+	 * if while servicing the readahead request the server triggers reclaim
+	 * and reclaim evicts the inode of the file being read ahead.
+	 */
+	ff = fuse_file_alloc(fm, release);
 	if (!ff)
 		return ERR_PTR(-ENOMEM);
 
@@ -152,13 +163,14 @@ struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid,
 			fuse_file_free(ff);
 			return ERR_PTR(err);
 		} else {
-			/* No release needed */
-			kfree(ff->args);
-			ff->args = NULL;
-			if (isdir)
+			if (isdir) {
+				/* No release needed */
+				kfree(ff->args);
+				ff->args = NULL;
 				fc->no_opendir = 1;
-			else
+			} else {
 				fc->no_open = 1;
+			}
 		}
 	}
 
@@ -363,7 +375,7 @@ void fuse_file_release(struct inode *inode, struct fuse_file *ff,
 	 * own ref to the file, the IO completion has to drop the ref, which is
 	 * how the fuse server can end up closing its clients' files.
 	 */
-	fuse_file_put(ff, false);
+	fuse_file_put(ff, false, isdir);
 }
 
 void fuse_release_common(struct file *file, bool isdir)
@@ -394,7 +406,7 @@ void fuse_sync_release(struct fuse_inode *fi, struct fuse_file *ff,
 {
 	WARN_ON(refcount_read(&ff->count) > 1);
 	fuse_prepare_release(fi, ff, flags, FUSE_RELEASE, true);
-	fuse_file_put(ff, true);
+	fuse_file_put(ff, true, false);
 }
 EXPORT_SYMBOL_GPL(fuse_sync_release);
 
@@ -891,7 +903,7 @@ static void fuse_readpages_end(struct fuse_mount *fm, struct fuse_args *args,
 		folio_put(ap->folios[i]);
 	}
 	if (ia->ff)
-		fuse_file_put(ia->ff, false);
+		fuse_file_put(ia->ff, false, false);
 
 	fuse_io_free(ia);
 }
@@ -1815,7 +1827,7 @@ static void fuse_writepage_free(struct fuse_writepage_args *wpa)
 	if (wpa->bucket)
 		fuse_sync_bucket_dec(wpa->bucket);
 
-	fuse_file_put(wpa->ia.ff, false);
+	fuse_file_put(wpa->ia.ff, false, false);
 
 	kfree(ap->folios);
 	kfree(wpa);
@@ -1968,7 +1980,7 @@ int fuse_write_inode(struct inode *inode, struct writeback_control *wbc)
 	ff = __fuse_write_file_get(fi);
 	err = fuse_flush_times(inode, ff);
 	if (ff)
-		fuse_file_put(ff, false);
+		fuse_file_put(ff, false, false);
 
 	return err;
 }
@@ -2186,7 +2198,7 @@ static int fuse_iomap_writeback_submit(struct iomap_writepage_ctx *wpc,
 	}
 
 	if (data->ff)
-		fuse_file_put(data->ff, false);
+		fuse_file_put(data->ff, false, false);
 
 	return error;
 }
-- 
2.47.3[PATCH v2 1/1] fuse: fix readahead reclaim deadlockJoanne Koong <joannelkoong@gmail.com> undefinedmiklos@szeredi.hu undefined undefined undefined undefined undefined undefined undefined